Isotopes of ruthenium

Naturally occurring ruthenium (Ru) is composed of seven stable isotopes. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life of 373.59 days, 103Ru with a half-life of 39.26 days and 97Ru with a half-life of 2.9 days.

Twenty-four other radioisotopes have been characterized with atomic weights ranging from 86.95 u (87Ru) to 119.95 u (120Ru). Most of these have half-lives that are less than five minutes, excepting 95Ru (half-life: 1.643 hours) and 105Ru (half-life: 4.44 hours).

Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the atomic mass may exceed the stated value for such specimens.

Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.

Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.